1. Field of the Invention
The present invention relates to a power assist device, a method of controlling the power assist device, and a program of the power assist device that are able to calculate operating force to a workpiece with high accuracy and to optimally perform power assist.
2. Description of Related Art
Various power assist devices are known that are able to suspend a workpiece by a wire to move the workpiece to a desired position according to manipulation by an operator. On the other hand, the operation method is to perform a button operation by an operation part to move the workpiece up and down or in a parallel direction, and its operability is not good.
On the other hand, such a power assist device is known to detect an average load applied to a wire by a force sensor as a reference load, calculates the operating force to the workpiece from the difference between the reference load and the current load from the force sensor, and drives a motor in an assist direction (see, for example, Japanese Unexamined Patent Application Publication No. 5-310396).
However, the power assist device disclosed in Japanese Unexamined Patent Application Publication No. 5-310396 stated above detects the load using a single force sensor. Accordingly, when there is a change in the reference load, for example, it may be difficult to calculate the operating force with high accuracy and power assist may not be optimally performed.
The present invention has been made in order to solve such problems, and mainly aims to provide a power assist device, a method of controlling the power assist device, and a program of the power assist device that are able to calculate operating force to a workpiece with high accuracy and to optimally perform power assist.